Pretty sure your car has a hydraulic clutch.
I would check the clutch fluid and make sure its full, then bleed the clutch to make sure there isnt any air in the system.
If none of that fixes it, its probably the clutch master cylinder or slave cylinder.
The reason its doing it in 1st and reverse is, well, your stopped. The only time you ever REALLY have to use the clutch is from a take off..
No offense, but asking mechanic advice on a car audio forum is like asking a mechanic for car audio advice... Theres people who know both, but most of them time:crap: